The present invention relates to a new and improved electronic device for monitoring a plurality of running threads on a textile machine.
For monitoring a plurality of running threads on textile machines such as warper's creels (bobbin creels), knitting, winding or spooling and spinning machines, mechano-electric or electronic thread monitors are employed.
In German Patent Publication No. 1,535,159 and German Pat. No. 2,544,528, mechano-electric thread monitors are described in which each individual thread cooperates with a mechanical sensor or feeler element. This sensor element changes its position due to breakage of the thread and thus supplies an easily recognizable, individual indication of the location of the defect. At the same time an alarm or switch-off signal for the machine can be triggered by closing an electric circuit. All thread monitors in which the thread is sensed by a mechanical element, such as a lever or a drop pin, will respond to the tension of the thread. Thus, they cannot differentiate between a running thread and a stationary thread under tension. With thread breakages between the sensor or feeler element and the draw-off or wind-up position, it happens not infrequently that the end of the thread connected with the sensor element remains under tension due to being jammed or stuck on parts of the machine, so that thread breakages of this type are not detected by the thread monitor.
Electronic thread monitors do not have this fault since they are able to differentiate, on the one hand, between a running thread, and, on the other hand, a missing or stopped thread. Such a thread monitor for a warping machine is described in Swiss Pat. No. 440,073. Here, the output signals from the individual work positions are fed to a common switching amplifier via a collecting line.
Since a thread breakage is not easily recognized with an electronic thread monitor on a machine having a great number of work positions, special indicators, such as light-emitting diodes, would have to be provided, for individual indication, at all work positions. However, these would react not only to a thread rupture or breakage, but also to a standstill of the machine. In other words, every time the machine is stopped for whatever reason, all indicators will always respond. It is desirable, however, that thread breakage is indicated clearly and only at the running position of the thread at which the breakage has occurred.